A liquid crystal display device is widely used now because of excellent features of low voltage operation and thin type display, and the like. A TN (Twisted Nematic), a STN (Super-Twisted Nematic), or an active matrix (TFT: thin film transistor) based on the TN, and the like are used for the display type of the conventional liquid crystal display device, which use a liquid crystal composition with a positive dielectric anisotropy value. However, narrowness of a viewing angle is one of weak points for these display types, and its improvement is a big problem with the greater demand of enlargement of a liquid crystal panel in recent years.
In order to solve this problem, display modes such as vertical alignment mode, IPS (In-Plane-Switching) and the like have newly been put into practical use in recent years. The vertical alignment mode is the mode aimed at improving the viewing angle by use of vertical orientation of liquid crystal molecules, which uses liquid crystal compositions having negative dielectric anisotropy (Δ∈). On the other hand, IPS is the method aimed at improving the viewing angle by switching the liquid crystal molecules using horizontal lateral electric field against a glass substrate, which liquid crystal composition having positive Δ∈ or negative Δ∈ is used. Thus, the liquid crystal compound and liquid crystal composition having negative Δ∈ are necessary as the vertical alignment mode and the IPS for the effective display modes which improve the viewing angle, and they have been desired strongly. Formerly, compounds having 2,3-difluorophenylene group have been mainly used as the composition having negative Δ∈ (as refer to patent document 1). However, a problem exists that the absolute value of Δ∈ of the liquid crystal composition using the compound is not sufficiently large (as refer to patent document 2) .
Therefore, a trifluoronaphthalene derivative is reported as a compound having negative Δ∈ of a larger absolute value than the compound having 2,3-difluorophenylene group (as refer to patent document 3). However, the demand for further reducing the consumption of electric power in a liquid crystal display device is strong, and, in this issue, the absolute value of Δ∈ is not sufficiently large even in case of using a trifluoronaphthalene moiety.
On the other hand, a compound having a trifluoromethyl group at a lateral position of benzene ring (as refer to patent document 4) is reported. Furthermore, it is also reported that the compound described in the cited document can be advantageously used as an element of the liquid crystal composition having negative Δ∈ of a larger absolute value. However, the compound having a trifluoromethyl group at a lateral position of benzene ring has a problem that the absolute value of dielectric anisotropy does not attain sufficiently large because of the following reason. That is, in the compound having negative Δ∈, in order to make the absolute value of Δ∈ larger, it is necessary to replace substituent groups having large electron-withdrawing group at a lateral position of benzene. However, since a 1,4-phenylene group has only two lateral substituent positions as 2-substituted position and 3-substituted position, a limit to increase the absolute value of Δ∈ exists.                Moreover, in the structure such as a biphenyl moiety which is connected with two 1,4-phenylene groups, the electron-withdrawing group replaced on two adjacency phenylene groups hardly turns to the same direction, and the absolute value of Δ∈ does not generally increase.        Thus, as mentioned above, development of the compound having an absolute value of larger Δ∈ in a negative Δ∈ compound has been desired.        
Patent document 1: JP-T-H02-503441
Patent document 2: JP-A-H10-176167
Patent document 3: DE: 195 22 195 Description
Patent document 4: JP-A-H08-40953